<?php

/*
 * Enano - an open-source CMS capable of wiki functions, Drupal-like sidebar blocks, and everything in between
 * Copyright (C) 2006-2009 Dan Fuhry
 * hmac.php - HMAC cryptographic functions
 *
 * This program is Free Software; you can redistribute and/or modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for details.
 */

function hmac_core($message, $key, $hashfunc)
{
	if ( strlen($key) % 2 == 1 )
		$key .= '0';
	
	if ( strlen($key) > 128 )
		$key = $hashfunc($key);
	
	while ( strlen($key) < 128 )
	{
		$key .= '00';
	}
	$opad = hmac_hexbytearray($key);
	$ipad = $opad;
	for ( $i = 0; $i < count($ipad); $i++ )
	{
		$opad[$i] = $opad[$i] ^ 0x5c;
		$ipad[$i] = $ipad[$i] ^ 0x36;
	}
	$opad = hmac_bytearraytostring($opad);
	$ipad = hmac_bytearraytostring($ipad);
	return $hashfunc($opad . hexdecode($hashfunc($ipad . $message)));
}

function hmac_hexbytearray($val)
{
	$val = hexdecode($val);
	return hmac_bytearray($val);
}

function hmac_bytearray($val)
{
	$val = str_split($val, 1);
	foreach ( $val as &$char )
	{
		$char = ord($char);
	}
	return $val;
}

function hmac_bytearraytostring($val)
{
	foreach ( $val as &$char )
	{
		$char = chr($char);
	}
	return implode('', $val);
}

function hmac_md5($message, $key)
{
	return hmac_core($message, $key, 'md5');
}

function hmac_sha1($message, $key)
{
	return hmac_core($message, $key, 'sha1');
}

function hmac_sha256($message, $key)
{
	require_once(ENANO_ROOT . '/includes/math.php');
	require_once(ENANO_ROOT . '/includes/diffiehellman.php');
	return hmac_core($message, $key, 'sha256');
}

?>